title: Tissue-specific regulation of aromatase promoter II by the orphan nuclear receptor LRH-1 in breast adipose stromal fibroblasts.
abstract: In postmenopausal breast cancers, the increase in aromatase expression observed in tumour associated adipose stromal cells is mediated via the upregulation of promoter II (PII) transcription. Factors such as PGE₂ which are secreted from breast carcinomas induce PII expression. The orphan nuclear receptor LRH-1/NR5A2 is one of the critical downstream transcriptional mediators of this effect. The aim of the current study was to determine whether LRH-1 could bind directly to PII and whether the suppression of LRH-1 expression could inhibit aromatase expression in human adipose stromal fibroblasts. Chromatin immunoprecipitation demonstrated endogenous LRH-1 occupancy on PII under basal conditions and with treatment with forskolin and phorbol 12-myristate 13-acetate (PMA). To assess the impact of LRH-1 knockdown on FSK/PMA mediated PII expression, cells were transfected with shRNA targeted against LRH-1 (shLRH-1) and treated with forskolin and PMA. A decrease in LRH-1, PII and total aromatase mRNA transcripts was observed in shLRH-1 transfected cells compared to controls under basal and treatment conditions. The results of this study support the hypothesis that suppression of LRH-1 may potentially be beneficial in the tissue specific regulation of aromatase expression in post menopausal breast cancer.
authors.affiliation: Prince Henry's Institute, Monash Medical Centre, 246 Clayton Road, Clayton, Melbourne, Vic 3168, Australia. ashwini.chand@princehenrys.org
authors.forename: Ashwini L
authors.initials: AL
authors.lastname: Chand
authors.forename: Kerrie A
authors.initials: KA
authors.lastname: Herridge
authors.forename: Tamara L
authors.initials: TL
authors.lastname: Howard
authors.forename: Evan R
authors.initials: ER
authors.lastname: Simpson
authors.forename: Colin D
authors.initials: CD
authors.lastname: Clyne
mesh_terms: D000273:Adipose Tissue / Q000201:enzymology*; D001141:Aromatase / Q000235:genetics*; D001940:Breast / Q000201:enzymology*; D001943:Breast Neoplasms / Q000235:genetics; D047369:Chromatin Immunoprecipitation; D005576:Colforsin / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D055786:Gene Knockout Techniques; D006801:Humans; D009928:Organ Specificity; D017698:Postmenopause / Q000378:metabolism; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D017154:Stromal Cells / Q000201:enzymology; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology; D014162:Transfection
chemical_list: C082631:NR5A2 protein, human; D034741:RNA, Small Interfering; D018160:Receptors, Cytoplasmic and Nuclear; D005576:Colforsin; C016658:phorbolol myristate acetate; D001141:Aromatase; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate